PLATE 13.— Diatomacese. 



Figure 



1 . Hyalosira rectangula, front view of connected frustules. 



2. Isthmia enervis, front view. 



3. LicmopTiora splendida. 5, side view ; c, front view of single frustule. 



4. Lithodesmium undulatum. a, front view ; 5, side view. 



5. Melosira nummuloides, front view. 



6. MeIosi7'a varians, front view, r/, side view. 



7. Meridion circulare. «, frustules united into a coil, front view ; b, side view of 



single frustule. 



8. Micromega parasitica^ natural size. 6, portion of a filament containing the 



frustules ; e, side view, c?, front view of a frustule. 



9. Nitzschia sigmoidea. a, side view ; b, front view. 



10. Nitzschia lanceolata. a, front view; 6, separate valve; c, side view of the same. 



1 1 . Nitzschia longissima. «, side view ; by front view. 



1 2. Nitzschia reversa, front view of single valve. 



13. Nitzschia acicularisy left-hand frustule; iV^. acicularis, right-hand frustule. 



14. Odontidium turgidulum. «, frustules united, front view ; ^, single valve, side 



view. 



15. Orthosira DicJcieii. «, front view ; 5, side view. 



16. Pododiscusjamaicensis. a, side view ; 6, front view. 



17. Podosphenia lEhrenbergii. «, front view; 5, side view of single frustule. 



18. Rhabdonema arcuatum. «, united frustules, front view ; 5, side view of single 



frustule. 



19. Rhipidoptera paradoxa. b, front view of single frustule; c, side view of the same. 



20. Striatella unipunctata. «, front view ; 5, the same ; c, side view. 



21. Surirella gejmna. «, side view ; 5, front view. 



22. Surii'ella bifrons. «, front view ; 5, side view. 



23. Synedra splendens. a, attached frustules ; 5, side view of prepared frustule ; 



c, front ^-iew of the same. 



24. Synedra ful gens, a, side view; 6, front view of a prepared frustule. 



25. Synedra capitata, side view. 



26. Sphenosira catena, a, united frustules, front view; by side view of single frustule. 



27. Tabellaria jiocculosa. a, united frustules, front view ; by side view of single 



frustule. 



28. Tetracyclus lacustris, united frustules, front view. «, side view. 



29. Triceratium favus. a, side view ; b, front view. 



30. Tryblionella scutellumy side view. 



31. T?yblioneIla gracilis, front view. 



32. Tryblio7iella gracilis, diagram of transverse section. 



